CHAPTER XII
LIQUID FUELS
Important factors in the choice of a liquid fuel for use in portable internal combustion engines are: (1) low cost; (2) ease and safety of transportation or storage; (3) high volatility, i.e., readily convertible into vapour; (4) non-corrosive action on metals; (5) high heat efficiency; (6) ability to give satisfactory results in existing types of internal combustion engine.
=Petrol= is a liquid fuel composed of carbon (C) and hydrogen (H) in chemical combination. The principal method of producing petrol is by distillation of crude petroleum. The best mixture to use in a petrol engine is one composed of 2 cubic feet of petrol vapour to every 98 cubic feet of air. Petrol does not require any heat to vaporize it under ordinary atmospheric conditions. _Pre-ignition_ of the charge is liable to occur if the compression pressure exceeds 100 lbs. per square inch. It does not corrode or deteriorate metal parts, but leaves a black carbon deposit if not properly burned. Its volatility is high and its specific gravity is low, being about 0·71. An average figure for the calorific value of petrol would be 20,000 B. Th. U. per lb. Petrol is very expensive and also needs care in handling. Private motorists are not allowed to _store_ petrol or benzol.
=Benzol= is a liquid fuel containing more carbon (C) and less hydrogen (H) than petrol. The principal method of obtaining benzol is by distillation of coal tar. The strength of the mixture should be such that a little more air is supplied in proportion to the quantity of fuel used than is required for petrol. Generally, it may be said that when an engine has been running on petrol and is changed over to benzol the size of the carburettor jet orifice should be slightly reduced and the weight of the float increased—no other changes need be made anywhere. Benzol is very volatile and also highly dangerous to handle, on account of its low flash-point. It often contains impurities which attack the metal parts of the engine and gum up the valves. It is more liable to deposit carbon than petrol. Benzol attacks rubber, and paint on coachwork. It is as expensive as petrol at the present time. The specific gravity of benzol may be taken as 0·88 and its calorific value as 19,000 B. Th. U. per lb. It may be compressed above 100 lbs. per square inch without pre-igniting.
=Alcohol= is a liquid fuel composed of carbon (C), hydrogen (H), and oxygen (O). The principal method of obtaining alcohol is from the fermentation of vegetable matter, such as potatoes, beetroot, etc. About 6 cubic feet of vaporized alcohol to every 94 cubic feet of air should be used. The volatility of alcohol is very poor compared with petrol or benzol, and it generally contains some water in suspension. It will stand double the compression pressure of petrol without pre-igniting. Alcohol is not so liable to deposit carbon as petrol or benzol, but is very liable to cause rust. It is not obtainable as a fuel in Great Britain at present, owing to the high duty on it. Engines for use with alcohol ought really to be specially constructed for the purpose. Its calorific value is only 12,000 B. Th. U. per lb., and its specific gravity is 0·82. Alcohol requires to be heated before it will vaporize, this heat generally being obtained from the exhaust gases after the engine has been first started up. Alcohol is fairly safe to handle or store.
=Paraffin= is obtained during the distillation of petrol from crude petroleum, and consists of carbon (C) and hydrogen (H) in _almost_ the same proportions as petrol. Its volatility is low, and it requires heat to vaporize it. The heat required for vaporization is usually obtained from the exhaust gases after the engine has been got running. In starting up a lamp must be used for heating the vaporizer of the carburettor. Paraffin will stand a little higher compression than petrol before pre-igniting. The specific gravity of paraffin may be taken as 0·80 and its calorific value as 18,000 B. Th. U. per lb. It is much cheaper than either petrol or benzol, being only about one-third of the cost. The chief objections to its use are its smell and the greasy character of the stain left by it on coachwork or clothes; also the difficulty of having to heat the vaporizing chamber of the carburettor. It is much safer to handle and store than either petrol or benzol, and requires about the same proportion of air to form an explosive mixture as that given for petrol. The range of variation of strength in the mixture which is permissible with paraffin is much less than with either petrol, benzol, or alcohol. Alcohol has the greatest range of variation in mixture strength. Paraffin is also very liable to deposit carbon, owing to the small range of variation permissible in the strength of the mixture.
=Thermal Efficiency.=—In the foregoing notes we have used certain terms which have not previously been explained, and therefore it is necessary to give one or two definitions.
The _Specific Gravity_ of a fuel is the ratio of the weight of one gallon of the fuel to the weight of one gallon of water. As a gallon of water weighs 10 lbs., it will be evident from the above notes that a gallon of petrol only weighs 7·1 lbs., whereas a gallon of benzol will weigh 8·8 lbs. (approx.), hence it is not surprising to learn that more _mileage per gallon_ is obtained with benzol than with petrol, even though the calorific value of benzol, per lb., is less than that of petrol. Sometimes the specific gravity is referred to as the _density_ of the fuel, but this is only correct when grammes and centimetres are being used. The density of any fuel is the weight of 1 cubic foot expressed in pounds or, in general terms, the mass of unit volume of the fuel. The _density_ of petrol in English units would be about 44 lbs. per cubic foot.
One _British Thermal Unit_ is the quantity of heat required to raise the temperature of 1 lb. of water by 1 degree (Fahrenheit scale) when the temperature of the water is about 60°F.
The _Calorific Value_ of any fuel (reckoned on the British system of units) is the amount of heat (expressed in British Thermal Units) which will be given out by 1 lb. of the fuel when it is completely burned. The liquid fuels we have to deal with are hydrocarbon compounds, and when completely burned the whole of the carbon is burned to carbon dioxide (CO_{2}) and the hydrogen to steam (H_{2}O), leaving no residue. By means of a _calorimeter_ we can experimentally determine the calorific value of any fuel.
It has long been known that work can be turned into heat, and the petrol engine is a good example of the reverse process which consists in turning heat into work. In a steam engine and boiler plant the heat of the fuel is liberated under the boiler, and then a portion of it gets transferred to the water in the boiler and forms steam, which is then taken to the engine and does work in the cylinder, the whole being a wasteful process. The petrol engine is an _internal combustion_ engine, or one in which the fuel is burnt inside the engine cylinder itself and converted directly into work. From every British Thermal Unit of heat liberated by the combustion of the fuel in the cylinder we should be able to get 778 foot-pounds of work if the _thermal_ (or heat) _efficiency_ of the engine was 100 per cent. The thermal efficiency (η) of any engine may be defined as the ratio which the heat equivalent of the work done per minute by the engine bears to the heat which would be liberated by the complete combustion of the quantity of fuel admitted to the cylinder per minute. Thus—
(Horse-power of the Engine × 33,000)/778 η = ——————————————————————————————————————————————————————————— (Number of pounds of fuel consumed per minute) × (Calorific Value of the fuel)
_Example_:—An engine developing 30 horse-power uses 0·50 lb. of benzol per minute. What is its thermal efficiency? The calorific value of benzol may be taken as 19,000 B. Th. U. per lb.
η = (30 × 33,000/778)/(0·50 × 19,000) = 0·134, or 13·4 per cent.
APPENDIX
ENGINE TROUBLES
Many of the troubles that are likely to arise have already been referred to in previous chapters, but the following additional notes may be found useful.
=1. Engine refuses to start.=
Care must be taken to observe exactly what happens, and one cannot do better than ask oneself mentally some of the following questions.
(_a_) _Is the ignition “on”?_
If a magneto is fitted the earth connexion should be open, but if a coil and accumulator are fitted the earth connexion should be closed.
(_b_) _Is the petrol reaching the carburettor jet?_
Before removing the jet for the purpose of examining and cleaning it, it would be advisable to ascertain whether the petrol was reaching the float chamber. Provided there is a reasonable amount of petrol in the tank and the tap is turned on, there must be a stoppage either in the petrol filter, the petrol pipe, or the bottom portion of the float chamber. Examine the filter and float chamber before disconnecting any pipes.
(_c_) _Is there a good compression in all the cylinders?_
If there does not appear to be any compression in any of the cylinders, it is probable that the carburettor throttle is closed and no air or gas can enter the cylinders. If there is a good compression in some cylinders and a poor one or none at all in others then—
(1) One or more of the valves may be held off its seat by dirt, by distortion, or by some derangement of the valve gear. Examine the valve gear externally, turning the engine slowly to watch its action. Afterwards remove valve caps and inspect valves if necessary.
(2) One or more of the sparking plugs or valve caps may be short of its washer. In this case the blow will be heard as the engine is turned round by hand.
(3) A piston may be cracked or broken or a cylinder cracked.
(4) A cylinder may have got badly worn and the rings on the piston jammed so that they no longer keep it gas-tight.
(_d_) _Is the engine very stiff to turn over?_
Stiffness is due as a rule to lack of oil on the cylinder walls, caused by absence of oil in crankchamber or the film of oil on the cylinder walls having been washed off when _priming_ the engine with petrol in attempting to start it. If a connecting rod is bent, or the crankshaft distorted or a piston ring broken, stiffness will also be noted. Very often by removing the valve caps and pouring a teaspoonful of oil or paraffin into each cylinder the engine may be freed by vigorously turning the starting handle by hand until the cylinders and pistons are well lubricated.
(_e_) _Is there any sign of an attempt to fire the charge_ such as an occasional puff of smoke from the exhaust or inlet, or an occasional jerk round of the engine as you turn the starting handle, or an occasional “bang” in the exhaust box?
If the ignition is “_on_” and the carburettor jet clear, the compression good and the engine quite free, yet there is no sign of a “fire” from any of the cylinders, it is possible that air is leaking into the induction pipe through a faulty joint or any one of the following ignition troubles may have occurred:—
(_f_) _Defective sparking plug or plugs._ This may arise from water or oil or dirt between the plug points; or from faulty insulation in the body of the plug. To test whether the plugs are at fault an easy method is to take a screwdriver with a wooden handle and place the metal blade on the terminal of the plug, letting the point come about one thirty-second of an inch from the metal of the cylinder or any of the pipes; when the engine is turned by hand the spark will be seen to pass across this improvised gap if the magneto and leads are in order.
(_g_) _Defective electrical connexions._
The high tension cables may be broken, or disconnected, or short-circuited. The _earth_ wire may be short-circuited (i.e., in electrical contact with some other wire or metal fitting). There may be a short-circuit in the ignition switch.
(_h_) _Defective magneto or coil._
The low tension contact breaker lever may be jammed so that the make and break is inoperative, or one of the carbon brushes may have got broken. Occasionally one finds the magnets of the machine have lost their power; or there is some electrical defect in the armature or condenser. The battery may have become exhausted. The trembler blade may be stuck up. Water may have found its way on to the high tension electrode or into the safety spark gap.
=2. Engine starts up fairly well, runs a little, and then stops.=
Take care to notice the manner in which the engine runs and stops. Note whether it runs regularly or irregularly and for how long a time.
If the engine runs _regularly_ with all cylinders firing, then probably the exhaust is choked or the petrol supply fails. Failure of the petrol supply may be due to the use of too small a jet in the carburettor, too low a level in the float chamber, or to partial stoppage in the pipe line. Another cause of this trouble of intermittent running would sometimes be loss of battery power when using coil ignition, i.e., batteries want recharging.
If the engine runs _irregularly_ the trouble is probably due to too much oil in the cylinders causing the plugs to _misfire_, the presence of water or dirt in the petrol, a defective valve, a broken carbon brush, or poor electrical contact somewhere in the magneto, the low tension contact breaker (coil), or high tension distributor (coil).
To ascertain whether the engine is firing regularly on all cylinders, or to detect which cylinder is _misfiring_, the best procedure is to open the compression taps in turn while the engine is running and in each case speed up the engine while you have the tap open. Cylinders which are firing _well_ give a sharp _cracking_ noise, those which are not firing merely give a _hissing_ noise. If no compression taps are provided, each plug must be short-circuited to the frame in turn by the screwdriver method given above. The short-circuiting process causes a reduction in engine speed except on that plug which is already not firing. The method is not so good as the compression tap process, because the plugs often get oiled up during the short-circuiting process and the difficulty is accentuated.
=3. Timing the Ignition.=
My colleague, Mr. Oliver Mitchell, has pointed out to me that it is often impossible to tell directly when the piston is exactly at the top of its stroke, and he recommends a study of the accompanying Valve Setting Diagram (Figure 71). From this it will be seen that it is sufficiently near to bring the engine first of all to such a position that the exhaust valve has _just closed_; then make a chalk mark on the flywheel and give the engine one complete turn round; the piston will then be in the firing position if the flywheel is turned a shade backwards. Another method would be to _retard_ the ignition fully and time it so that the spark occurred one complete revolution after the _inlet_ valve had _just commenced to open_. When either valve is closed its tappet can be felt to be _free_, the amount of freedom depending upon the clearance between the tappet head and valve stem.
INDEX
A
Acceleration, quick, 78 — under load, 92
Accessibility, 39, 50
Accumulator, 61
Adapter, 92
Adjustable tappet head, 29, 30
Adjusting screws, 19
Advanced ignition, 55, 56, 59
Aeroplane engine cylinder, 10, 16
Air, 1, 41, 42, 46, 87, 89, 114 — carburetted, 42, 97 — lock, 72 — pump, 50 — — hand, 50 — scavenging, 16, 35, 84, 85, 87, 88, 89 — to petrol ratio, 42 — valve, automatic extra, 43, 49 — velocity, 46, 70 — volume of, relative to petrol vapour, 42, 108 — weight of, relative to petrol vapour, 42
Alcohol, properties of, 109
Anti-freezing solution, 72
Armature of magneto, 52, 54 — relative speeds of engine and magneto, 54, 55
Atmospheric pressure, 3, 90
Atomization of petrol, 48, 49
Automatic extra-air valve, 43, 49 — inlet valve, 82, 84, 88
B
Backfire, 62, 84
Balance, perfect, 76 — want of, 75, 76 — weight, 25
Balancing the crankshaft, 25, 26, 76
Barrel of cylinder, 12
Base, oil, 8, 40, 65
Battery, 116
Bearings, main, 24, 64
Benzol, properties of, 45, 108
Blade, trembler, 57
Boiling of water in jackets, 72
Boxes, core, 11
Brake, for petrol engine, 100
Brake horse-power, 99
British thermal unit, 111
Brush, carbon, 53, 55, 116
Built-up cylinder, 16 — flywheel, 27
Buoyancy, 45
Burning, rate of, of mixture, 1, 57 — of deflector, 91
Bursting of flywheel rim, 27
Bush, phosphor bronze, 23
C
Cables, high tension, 61
Calorific values, 111
Cam, 30, 33
Camshafts, 29, 33, 40
Cams, stationary, for magneto, 53
Capacity of cylinder, 106
Caps, valve, 13, 31
Carbon brush, 53, 55, 116 — deposit, 63, 78
Carburation, 42, 94
Carburetted air, 42, 97
Carburettor, 5, 8, 42, 82 — jet type, 42 — multiple jet, 47, 94 — points of a good, 49 — recent improvements in, 47 — spray type, 42 — surface type, 42 — wick type, 42
Castings, cylinder, 11
Cast-in-pairs, cylinders, 16
Centrifugal force, 27
Chaindrive, silent, 38
Charge, 3, 80
Charging pump, 80
Chassis, 40, 71
Choke tube, 46, 47
Chrome steel, 20, 36
Circulating water pump, 8, 71
Circulation, forced, 71 — local, 73 — pump, 71 — thermo-syphon, 69
Clearance between piston and
cylinder walls, 17 — of valve tappet, 29 — space, 4, 105, 107
Coil ignition, 57, 59, 61 — — system, wiring diagram for, 61 — non-trembler, 59 — supplementary, for starting, 58 — trembler pattern, 57, 61
Collector ring, 55
Combustion, 78 — chamber, 4, 96
Compensating jet, 48
Compression, meaning of, 3 — pressure, 82, 83, 105 — stroke, 6, 80
Cone clutch, 27
Connecting rod, 4, 21, 96 — — forces acting on, 20 — — phosphor bronze, 20, 22 — — steel, 23
Consumption of fuel, 79 — of oil, 67
Contact breaker, low tension, 53 — — wipe form of, 58 — screws, platinum tipped, 53, 57
Cooling, 69
Core-boxes, 11
Core, iron, of ignition coil, 57
Cost of production, 22, 64, 79
Cotter, 29
Crank chamber, 8, 39 — — gas-tight, 81, 82, 96 — cheeks or webs, 24 — motor-cycle, 23 — pin, 24 — radius, 4 — shaft, 23, 28, 77, 89
Crank shaft, balancing the, 25, 76 — — vibration of, 76 — — whipping of, 76
Cushion of hot gas, 93, 96
Cut-out, 90
Cycle, four-stroke, 5 — motor, 10, 11 — Otto, 5 — two-stroke, 80
Cylinder, 5, 9 — aeroplane engine, 15, 16 — air-cooled, 11, 15 — barrel, 12 — built-up, 16 — castings, 11 — head, detachable, 32, 78 — jackets, 12, 15, 69 — L-headed, 16 — pump, 87, 88, 107 — revolving, 10 — T-headed, 15 — water-cooled, 8, 32, 82, 96 — working, 81, 87, 107
Cylinders, cast _en bloc_, 16, 77 — cast in pairs, 16 — cast separately, 16 — choosing the number of, 75 — firing order of, 60
D
Dead centre, 4, 116 — gases, 83
Defective coil, 114, 116 — ignition system, 114 — magneto, 114, 116 — sparking plug, 113, 114 — valve, 113, 114, 116
Deflector, 81, 87, 93, 96 — overheating of, 84, 91
Density, 45, 111
Deposit of carbon, 63, 78
Description of a typical petrol engine, 8
Detachable cylinder head, 32, 78
Devices, ignition, 51
Diagram, indicator, 92, 102 — for four-stroke engine, 105 — for two-stroke engine, 106 — for valve setting, 116 — work, 103
Difficulties in starting, 72, 75, 92, 96, 113
Discharge, spark, 51, 54, 58
Distributor, high tension, 52, 53, 58
Double sleeve engine, 32, 78
Down stroke, 4, 81, 82
Drawings, working, 11, 93
Drip feed, 64, 90, 92
Drive, silent chain, 38
Dual ignition, 58 — springs, 90
Ducts for oil, 41
Duplex piston, 86
Durability, 49, 79
E
Earthing wire, 60
Eccentric, 33, 36 — rod, 33, 36 — sheaves, 33, 36 — straps, 33, 36
Economy and durability, 79
Efficiency, thermal, 110, 111 — volumetric, 83, 86, 88
Electric spark, 51, 54, 58
Electrodes of sparking plug, 51, 91, 92
Engine, four cylinder, 9, 76, 77, 94 — internal combustion, 111 — motor car, 9 — multi-cylinder, 77 — points of a good, 75 — single cylinder, 75 — six cylinder, 76, 77 — troubles, 113 — two cylinder, 76 — two-stroke, 80, 95
Evaporation, 1
Exhaust pipe, 6 — ports, 81, 88 — — open, 81, 88, 96 — smoky, 66 — stroke, 7, 35 — system, overheating of the, 57 — valves, 5, 10, 37, 81 — valves, timing of the, 35, 37, 78, 116
Explosion stroke, 7, 21, 26, 35
Explosive mixtures, 1, 108, 109, 110
Extra-air valve, 43, 49, 94
F
Fan, 70 — pulley, 8, 70
Feed, drip, 64, 90, 92
Fibre, tappet head, 30 — wheel, 38
Film of oil, 65
Filter, petrol, 43
Fins, heat radiating, 70
Firing order of the cylinders, 60 — stroke, 60
Fixed ignition, 57
Flanges, 12, 13
Flash point of lubricating oils, 63, 67, 68
Flashing back from exhaust, 84, 92, 93, 95
Flexibility, 77, 83, 92
Float chamber, 43, 44, 94
Flooding, 45, 94
Fluctuation of engine speed, 27
Flywheel, 8, 26 — built-up, 27 — function of, 26 — rim, bursting of, 27 — single stamping of steel, 28
Force, 98 — centrifugal, 27
Forced circulation, 71 — lubrication, 65, 90
Forces, inertia, 75 — space diagram, 103
Four cylinder engine, 9, 76, 77, 94 — stroke cycle, 5
Frequency of vibrations, 76
Fuel, consumption of, 79
Fuels, liquid, 108
Furring of tubes and jacket spaces, 73
G
Gap of sparking plug, 51, 54
Gas, compressing the, 3 — pump, 80 — tight crankchamber, 81, 82, 96
Gearing, overhead, 16
Gears, helical, 38
—spur, 37, 38
General overheating, 72, 73
—principles, 1
Gilled tube, 70, 74
Gills, 70
Gravity feed, 50
Grease in cylinder jackets, 72
Grinding in a valve, 31
Gudgeon pin, 17, 18 — — wear on, 19, 90
Guides, valve stem, 8, 12, 13, 30
H
Hand air pump, 50
Handle, starting, 71
Head, adjustable tappet, 30 — of water, 69, 71
Heat efficiency, 112 — energy of the petrol mixture, 9, 17, 111 — radiating fins, 11, 70 — surplus, 9, 17
Helical teeth, 38
High tension cables, 61 — — distributor, 52, 54, 58 — — magneto, 8, 51, 52, 54, 89 — — terminals, 51, 57
Holes, cotter, 29 — oil, 63
Honeycomb radiator, 70, 74
Horse-power, 98 — brake, 99 — indicated, 101 — Joint Committee’s formula, 101 — of car, 99 — Treasury formula, 101
Hot-water jacket, 43, 47, 94
Hydrogen, 108, 109
I
Idle stroke, 26, 82
Ignition, advanced, 55, 56, 59 — coil, 57, 59, 61 — devices, 51 — dual, 58 — fixed, 57 — knock, 57, 84 — normal, 55 — retarded, 55, 59, 62 — synchronized, 59, 61 — timing the, 60, 62, 116 — two-point, 59
Improved system of splash lubrication, 64
Improvements in carburettors, recent, 47
Indicated horse-power, 101
Indicator diagram, 92, 102 — — for four-stroke engine, 105 — — for two-stroke engine, 106
Indicator, optical, 92
Induction pipe, 5, 8, 43, 82
Inertia forces, 75
Inflammable vapour, 63
Injection of water to cylinder, 92
Inlet ports, 81, 88 — valve, air, automatic, 43, 49, 88 — — automatic, for gaseous mixture, 82, 88 — — mechanically operated, 5, 30, 31 — — timing the, 34, 37, 78, 116 — water pipe, 8, 70, 73
Inspection openings, 39
Insulators, 51
Internal water cooling, 92
J
Jacket, cylinder, 12, 15, 69 — hot water, 43, 47, 94 — space, too large, 73 — water, overheating of, 72 — — temperature of, 74 — — weight of, 74, 89
Jet, atomizing, 48 — compensating, 48 — petrol, 44, 46
Jet-in-tube carburettor, 42
Jigs, 24
Jockey pulley, 38
Joints, water-tight, 11, 15
Journals, 24
K
Kean’s two-stroke engine, 85, 94
Knock ignition, 57, 73, 84
Knocking, acceleration, 92, 93, 95 — intermittent, 84, 92, 93 — spasmodic, 84, 91
L
=L=-headed cylinders, 16
Lag in opening and closing valves, 34 — time, 56
Lead of valve, 35
Leakage of gas past the piston, 18, 114
Leaky pistons, 114
Liquid fuels, 108 — petrol, 108
Local circulation, 73 — overheating, 72
Lock, air, 72
Lock nuts, 29
Low tension contact breaker, 52 — — terminal, 57, 58 — torque, 75
Lubrication, forced, 65, 90 — improved system of splash, 64 — splash system of, 63
M
Magneto armature, relative speeds of, 54, 55, 94 — for four cylinder engine, 52, 54, 60 — for six cylinder engine, 54 — high tension, 8, 39, 40 — ignition system, wiring diagram for, 60 — racing pattern, 94 — two-stroke engine, 94
Make and break, 53, 58, 62
Manograph, 104
Materials, packing, 15
Mean effective pressure, 89, 107
Mechanically operated valve, 30, 84
Metal segments of distributor, 55
Mild steel, 23
Mileage per gallon, 110
Misfiring, 84, 116
Mixing chamber, 43, 47
Mixture, explosive, 1, 108, 109, 110 — heat energy of the, 9, 17, 111 — strength of the 1, 42, 108, 109, 110 — too weak a, 46 — weakening the, 49, 73
Momentum, 35, 36
Monobloc casting, 77
Motor car engine, 9 — cycle, 10, 11 — — crank, 23
Moulds, 11
Multiple jet carburettor, 47, 94
Mushroom type valves, 5, 8, 30
N
Natural circulation, 69
Needle valve, 44
Nickel steel, 20, 36
Noise from valves, 30, 39
Non-trembler coil, 59
Normal ignition, 55
O
Oil base, 8, 40, 65
— consumption of, 67 — ducts, 41 — film, 65 — holes, 63 — pressure, 65, 67 — price of, 67 — properties of, 63 — pump, 8, 39, 40, 65, 67 — — speed of, 67 — troughs, 65
Open exhaust port, 81, 88, 96
Optical indicator, 92
Orifice, 45, 73
Oscillations, torsional, of the crankshaft, 77
Otto cycle, 5
Outlet water pipe, 8, 70, 71, 73
Overflow pipe, 72
Overhead gearing, 16
Overheating of deflector, 84, 91 — of the exhaust system, 57 — general, 72, 73 — local, 72
Overloading the engine, 55, 89
P
Packing materials, 15 — rings, 17, 18, 81, 87, 97
Paraffin, properties of, 109
Partial seizure, 19, 33, 63, 64, 90 — vacuum, 6, 46, 82, 90
Passages, valve, 10
Patterns, 11
Perfect balance, 76, 77 — combustion, 78
Periodicity, 76, 77
Petrol, consumption of, 79 — engine, description of a typical, 8 — filter, 43 — jet, 44, 46 — mixture, heat energy of, 9, 17, 111 — pipe, 43 — properties of, 108 — supply, failure of, 113 — tank, 43 — tap, 43 — vapour, 1, 42, 43, 80 — — ratio of air to, 42
Phosphor bronze bush, 23 — — connecting rod, 22
Pinking, 79
Pipe, exhaust, 6, 8 — induction, 5, 8, 43, 82 — inlet water, 8, 70, 71, 73 — outlet water, 8, 70, 71, 73 — overflow, 72 — transfer, 86, 87 — vent, 39
Piston, 4, 17, 32, 82, 96 — duplex, 86 — leaky, 73, 114 — ring, cast-iron, 18, 82 — — steel, 19 — seizure of the, 19, 33 — steel, 19 — weight of, 19
Pitch of the teeth on a gear wheel, 38
Plain tube radiator, 74
Platinum tipped contact screws, 53, 57
Plug, sparking, 5, 8, 51, 91, 92
Points of a good carburettor, 49 — — good engine, 75
Poppet valve, 29, 77, 79
Ports, exhaust, 33, 78, 81, 88 — inlet, 33, 78, 81, 88 — open exhaust, 81, 88, 96
Power, 98 — stroke, 7, 60, 80
Pre-ignition, 84, 90, 92, 95, 108, 109, 110
Pressure, atmospheric, 3, 90 — compression, 3, 80, 82, 83, 88, 105 — feed, 50 — mean-effective, 89, 107 — of oil, 65, 67
Prices of oils, 67
Primary winding, 53, 58
Production, cost of, 22, 64, 79
Properties of fuels, 108, 109, 110 — of oils, 63
Pulley, fan, 8, 70 — jockey, 38
Pump, air, 50 — charging, 80 — circulating, 8, 67, 71 — cylinder, 87, 88, 107 — gas, 80 — hand air, 50 — oil, 8, 39, 40, 65, 67 — piston, 86 — water, 8, 39, 71
Push rod, 29
Q
Quick acceleration, 78, 92 — make and break, 53, 59, 62
R
Racing pattern magneto, 94
Radiator, gilled tube, 69 — honeycomb, 70, 74 — size of, 71, 72, 74, 89
Rate of burning, 1, 57
Rated horse-power, 101
Ratio of air to petrol vapour, 42
Recent improvements in carburettors, 47
Relative speeds of engine and magneto, 54, 94
Release of gases, 105
Relief valves, 67
Residue, 63
Retarded ignition, 55, 57, 59, 62
Revolving cylinders, 10
Ring, packing, 17, 18, 81, 87, 97 — steel piston, 19
Roller, 29, 58
Rotary valves, 79
S
Sagging of camshaft, 36
Scavenging, 16, 35, 84, 85, 87, 88,89, 93
Scoops, 65
Screws, adjusting, for gudgeon pin, 18 — platinum tipped, for contact breaker, 53, 57
Seat of valve, 13, 29
Segments, metal, of distributor, 55
Seizure of piston, 19, 33, 63, 64, 90
Shafts, eccentric, 33
Sheaves, eccentric, 33
Short-circuiting terminal, 55
Silence in running, 79, 92, 95
Silencer, 6, 89
Silent chain drive, 38
Simple two-stroke engine, 81, 85
Single cylinder engine, 75, 76 — sleeve valve engine, 32 — throw crankshaft, 23
Six cylinder engine, 76 — — — magneto for, 54
Sleeve valves, 32, 77, 78
Sleeves, double, 32, 78
Slots, 32
Smoky exhaust, 66
Spark, electric, 51, 54, 58
Sparking plug, 5, 8, 13, 51, 91, 92
Spasmodic knocking, 84, 91
Specific gravity of fuels, 108, 109, 110
Speed, fluctuation of engine, 27 — of oil pump, 67
Speeds of magneto armature and distributor, 54, 55, 94
Splash system of lubrication, 63 — — — improved, 64
Split pin, 19
Spray type of carburettor, 42
Springs, dual, for automatic valve, 90 — valve, 8, 29, 90
Sprocket wheels, 38
Spur gears, 38
Stampings for connecting rods, 22
Starting difficulties, 72, 75, 92, 96 — handle, 8, 71
Stationary cams for magneto, 53
Steel, chrome nickel and chrome vanadium, 20, 36 — flywheel, built-up, 27 — — single stamping, 28 — mild, 23 — pistons, 19 — — rings, 19 — tungsten, for valves, 30 — Ubas, 90
Storage of petrol, 108
Strap, eccentric, 34
Strength and character of spark, 58 — of mixture, 1, 42, 108, 109, 110
Stroke, meaning of, 3 — suction, 6, 21, 35, 60, 80
Suction, meaning of, 2
Supplementary coil, for starting, 58
Surface carburettor, 42
Synchronized ignition, 59, 61
T
Tank, petrol, 43
Tap, compression, 13 — petrol, 43
Tappet head, 29, 30 — valve, 8, 29
Teeth, helical, 38 — pitch of, 38
Temperature of jacket water, 74
Terminals, high tension, 51, 57 — low tension, 57, 58
T-headed cylinder, 15
Thermal efficiency, 110, 111 — unit, British, 111
Thermo-syphon circulation, 69, 89
Three-port two-stroke engine, 97
Throttle valve, 44, 47
Time lag, 56
Timing the ignition, 60, 62, 116 — the inlet valve, 34, 37, 78, 116 — the exhaust valve, 35, 37, 78, 116 — wheels, 8, 37
Too rich a mixture, 46, 78
Too weak a mixture, 46, 73, 78
Torque, low, 75
Torsional oscillations of crankshaft, 77
Transfer pipe, 86, 87
Treasury rating for horse-power, 85, 101
Trembler blade, 57 — coil, 57, 61
Troughs, oil, 65
Tube, amount required for radiator, 74 — gilled, 74 — plain, 74
Tungsten-steel valves, 30
Twin piston two-stroke engine, 96
Two cylinder engine, 76
Two-point ignition, 59
Two-port two-stroke engine, 81, 85, 95
Two-stroke cycle, 80, 83, 87 — engine, Kean, 85, 94 — — simple, 81, 85 — — twin piston, 96 — — two-port, 81, 85, 95 — — three-port, 97 — — valveless, 97
U
Ubas steel, 90
Unbalanced mass, 25
Underframe, 40
Up-stroke, 4, 81
V
Vacuum, partial, 6, 46, 49, 82, 90
Valve, automatic inlet, 82, 84, 88 — — extra air, 43, 49, 88 — caps, 13, 31 — defective, 113, 114, 116 — exhaust, 5, 37, 81 — extra air, 43, 49, 94 — guides, 8 — head, 29 — inlet, 3, 5 — mechanically operated, 5, 30, 84 — mushroom type, 5, 8, 30 — needle, 44 — passages, 10 — relief, 67 — seat, 13, 29 — springs, 8, 29, 90 — stem guides, 8, 12, 13, 29 — tappet, 8, 29 — throttle, 44, 47 — timing the exhaust, 35, 37, 78, 116 — — the inlet, 34, 37, 78, 116 — to grind in, 31 — tungsten steel, 30
Valves, noise from, 30, 39 — poppet, 29, 77, 79 — rotary, 79 — sleeve, 32, 77, 79
Valveless two-stroke engine, 97
Valve-setting diagram, 116
Vanadium steel, 20, 36
Vaporization, 1, 46, 48, 49, 94
Vapour, inflammable, 63 — petrol, 1, 33, 42, 80
Velocity of air, 46, 70
Vent pipes, 39
Vibration of crankshaft, 76
Viscosity, 63
Volatility, 108
Volume displaced by piston, 105, 106, 107 — of clearance space, 4, 105, 107
Volumetric efficiency, 83, 86, 88
Vulcanite fibre tappet head, 30
W
Washer, 29
Waste heat, 9, 17
Water boiling in jackets, 72 — circulating pump, 8, 67, 71 — cooled cylinder, 8, 32, 82, 96 — cooling, internal, 92 — head of, 69, 71 — hot, for jacket, 43, 47, 94 — injection, 92 — jacket, 10, 12, 70, 72, 73, 96 — pipe, inlet, 8, 69, 70, 71, 73 — — outlet, 8, 69, 70, 71, 73 — pump, 8, 39, 40, 72
Water-tight joint, 11, 15
Weakening the mixture, 49, 73
Wear on gudgeon pins, 19, 90
Webs, crank, 24
Weight of piston, 19 — of water in radiator, 74, 89
Weights, balance, 25
Wheels, fibre, for timing gear, 38 — sprocket, for chain, 38 — timing, 8, 34
Whipping of crankshaft, 76
Wick type of carburettor, 42
Winding, primary or low tension, 53, 58, 61 — secondary or high tension, 53, 58
Wipe form of contact breaker, 58
Wire, earthing, 60
Wiring diagram for coil ignition system, 61 — — for magneto ignition system, 60
Work, 98 — diagram, 103
Working cylinder, 81, 87, 107 — drawings, 11, 93
Wrist pin, 18
(PR. 1315.)
Butler & Tanner Frome and London
* * * * *
Transcriber's Notes
Obvious typographical errors have been silently corrected. Variations in hyphenation have been standardised but all other spelling and punctuation remains unchanged.
Italics are represented thus _italic_, bold thus =bold= and underlining thus +underline+.
In several of the equations the final answer was presented in bold text. To avoid confusion with the mathematics this has not been indicated.